DBM#to_a

static VALUE
fdbm_to_a(VALUE obj)
{
    datum key, val;
    struct dbmdata *dbmp;
    DBM *dbm;
    VALUE ary;

    GetDBM2(obj, dbmp, dbm);
    ary = rb_ary_new();
    for (key = dbm_firstkey(dbm); key.dptr; key = dbm_nextkey(dbm)) {
        val = dbm_fetch(dbm, key);
        rb_ary_push(ary, rb_assoc_new(rb_str_new(key.dptr, key.dsize),
                                      rb_str_new(val.dptr, val.dsize)));
    }

    return ary;
}